Control mechanism



Feb. 13, J F SHANNQN CONTROL MECHANISM Filed May 8, 1947 I 2 Sheets-Sheet l FIG. I INVENTOR. 22 JACK F. SHANNON Feb. 13, 1951 SHANNON 2,541,299

CONTROL MECHANISM Filed May 8, 1947 2 Sheets-Sheet 2 AMPLIFIER AND MOTOR CONTROL ELECTRIC FURNACEZS POWER v CONTBQLLERS INVENTOR.

JACK F SHANNON Patented Feb. 13, 1951 CONTROL MECHANISM Jack F. Shannon, Euclid,

Meter Company,

Ohio, assignor to Bailey a corporation of Delaware Application May 8, 1947, Serial No. 746,696

Claims. 1 y

This invention relates to control mechanisms adapted especially for use with indicating or recording meters which operate automatically in accordance with changes in a variable condition to be measured.

It is sometimes desirable that there be provided with meters measuring a variable condition, apparatus for giving an alarm when the condition goes above or below predetermined values. It is also frequently desirable that there be provided control means which tend to maintain the condition at some predetermined value or within a predetermined range of values. Even when such control means are employed there may be times when the value of the condition becomes too high or too low, and the giving of a warning is necessary. The control means may be used in some cases to regulate something other than the condition being measured, and the alarm may be caused to operate if the regulation should become ineilective. In any case the control means and/or the alarm apparatus should be readily adjustable to operate at any desired value.

A preferred form of my invention may include relatively rotatable members operatively connected by a differential gearing mechanism in such a manner that rotation of either one of two members causes a third member to rotate with it, but has no eifect on the rotation of the other. Means may be provided for rotating one of the two members manually. while the other member is connected for rotation in accordance with variations in a condition. Connected to the last mentioned member and to the third member are actuating means for an alarm and for control devices. With such an arrangement, the actuating means carried by the third member may be readily adjusted manually so that it becomes eifective at any desired point, and then be actuated on changes in the condition to perform its function according to the adjustment made. If desired, both the alarm and the control devices may be connected to the third member so that they are adjusted simultaneously on rotation of the manually operated member.

An object of my invention is to provide alarm and control means arranged in an improved manner for manual adjustment and for actuation in accordance with variations in a condition. Another object is to provide control devices connected to a manually operable means and to means operating in accordance with a condition for selective adjustment by each. Still another object is to provide control devices the temperature in a furnace i.

connected through differential gearing to a manually operable member and to a mechanism operating in accordance with changes in a condition, the connections being such that the devices may be actuated by either the member or the mechanism. Yet another object is to provide improved means for indicating the setting of control devices which may be adjusted manually and which may be actuated from any adjustment in correspondence with variations in a condition. Other objects will appear in the course of the following description.

In the accompanying drawings in which there is shown for purposes of illustration, one form which my invention may assume in practice:

Fig. 1 is a view partially in section and partially in elevation, showing alarm and control devices arranged in accordance with my invention for manual adjustment and for actuation by a power mechanism.

Fig. 2 is a schematic diagram of a system in which my invention is adapted for use.

Fig. 3 is a view taken on the plane of the line l3 of Fig. 1.

Fig. 4 is a view taken on the plane of the line 4-4 of Fig. 1.

Referring to the drawings, and more particularly to Fig. 2, it will be noted that there is shown a system for measuring and controlling This system comprises a bridge 2 having an element 3 forming one of its legs and varying in resistance in accordance with the temperature in the furnace. A fixed resistance 4 forms another leg of the bridge, and resistors 5 and 6 combined with variable portions of a potentiometer 8. form the other pair of legs. A movable contact 9 for the potentiometer and a diagonally opposite point of the bridge are connected by conductors I0 and II to an amplifier and motor control which may be like that disclosed in the Ryder Patent 2,333,393 granted November 2; 1943. The other diagonal of the bridge is shown connected by conductors l2 and I4 to the secondary of a transformer l5, whose primary winding is connected to a source of alternating current. A motor I! is energized by the amplifier and motor control when the bridge is unbalanced and operates to position the contact 9 until a ba'ance is again obtained. An indicator or pen arm 20 may also be connected to the motor for indicating upon a scale 2| or recording on a chart 22 the value of the temperature.

The furnace is shown herein as an electric furnace heated by resistor elements 2! and 28 which are connected at one end to a power conductor 21 and are adapted to be connected at their opposite ends through power controllers or relays 2B and 28 to a power conductor 30. When both of the heating elements 25 and 25 are energized, the temperature within the furnace increases. If only one of the elements is energized, the temperature within the furnace may continue to increase slowly or may drop gradually to a lower value. The temperature may be maintained approximately at a predeter mined value by energizing both of the heating elements when the temperature is too low, deenergizing one of the elements at or slightly below the desired temperature, and deenergizing the other element if the temperature increases a given amount over the desired value. By energizing the elements again as soon as the temperature drops below the values at which they are deenergized, it will be seen that a close regulation of the furnace temperature may be obtained.

The power controllers or relays 25, 29 are adapted to operate when energized to connect the elements 25, 25 to the power line 30. For energizing the relays, there is provided a transformer 32 having its primary winding connected to a source of alternating current, and its secondary winding connected at one end through conductors 33 and 34 to one terminal on each of the relays. The other end of the secondary winding is connected to the other relay terminals through circuits 35 and 31 containing switches 35 and 39. Cams 40 and 4! are operatively connected to the motor is and act to hold the switches closed as long as the temperature remains below the values at which it is desired that the heating elements be deenergized. Formed in the cams are notches 44 and 45 into which the ends of switch contact arms may move for effecting an opening of the circuits 35 and 31.

When the temperature of the furnace is low, the cams 40, 4| may be in the positions shown in Fig. 2 for holding the switches 38, 3! closed and eifecting an operation of the relays 25, 29 to energize the elements 25, 25. As the temperature increases, the resistance of the element 3 changes and unbalances the bridge 2, causing an operation of the motor I!) to rotate the cams in a clockwise direction and to position the contact 9 for rebalancing the bridge. When the notch 44 moves under the end of the switch arm of the switch 38, the latter opens and effects a deenergization of the heating element 25. If the furnace temperature should continue to increase until the notch 45 moved under the end of the switch arm of switch 39, the latter would then open to eifect a deenergization of the heating element 25. With both of the heating elements deenergized, the temperature would then drop until switch 39 was again closed. If the temperature should continue to drop, switch 38 would soon be closed. Both of the heating elements would then be energized and the furnace temperature would increase.

A failure in the power line, or a failure in the switches 38, 39 or the relays 28, 29 may result in a drop or an increase in the furnace temperature beyond safe values. In order that the attendant may be warned when such conditions exist, there are provided alarms 48, 49, such as lights or bells, connected in circuits including switches 50 and Cams 52 and 53 driven by the motor I! hold the switches normally in open position, and are provided with notches 54 and 55 into which the ends of switch arms may move for closing the 4 switches and eflecting the energizing 'ot alarms, as by batteries 55. If the relays 25, 25 fail to disconnect the heating elements from the power line when the switches 55, 35 open, or i! the switches 48, 38 fail to open at the proper times, the furnace temperature continues to increase and effect operation of the motor I. to rotate the cams in a clockwise direction. when notch 54 moves under the arm of switch 55, the latter closes and energizes the bell or signal light 45. A failure in the power line results in an operation of the motor to rotate the cams in a counterclockwise direction. At a predetermined low temperature, notch 55 moves under the arm of switch 5|, causing the latter to close and complete the circuit through the light or bell 45.

The switches for controlling the alarm circuits and the control circuits may be provided, as shown in Figs. 3 and 4, with an arm 54 connected to a casing 59 and engageable with one of the cams at its free end. A contact member 44 is yieldably urged by a spring 5i against the arm for holding the latter against the cam. The contact members for the switches 35, 39, as shown in Fig. 3, are in open positions only when notches in the cams move into positions for receiving the ends of the arms, The contacts of switches 55, 5! are in open positions, as shown in Fig. 4, when the arms 55 ride on the outer periphery of the cams.

The improved supporting and actuating means for the cams 40, 41, 52 and 53 is shown in Fig. 1. In this case, a shaft 55 extends through an opening in a plate 55 arranged in a meter casing, not shown. Fixed to one end of the shaft is a knob 51 which may be grasped and rotated manually in either direction. Connected to the shaft 55 adjacent its other end is a bevel gear 55 meshing with a pinion gear 59 journaled on a member 14 which is fixed to a sleeve shaped member I l rotatably mounted on the shaft. Another bevel gear 12 meshes with the gear 59 and is fixed to a sleeve shaped member 14 rotatably supported by the member H. The earns 40, 41 are fixed to the member H, and the earns 52, 53 are fixed to the sleeve member 14. The motor I! drives a. gear 15 meshing with a gear 11 fixed to a hub 15 of the bevel gear 12. The gears 55, 59 and 12 form a differential gearing connecting the sleeve member H for actuation by either the knob 5'! or the motor 19.

When the shaft 55 is rotated manually, the gear 58 turns with it and causes the gear 55 to rotate and travel around the gear 12 which is held against rotation by reason of its connection through the gears 15, 11 to the motor l9. As the gear 59 travels around the gear 12, it rotates the sleeve member H and positions the cams 4|, 4| relative to the switches 38, 38. Carried by the shaft 55 is a collar 80, and a bowed spring plate BI is arranged between the collar and a stationary frame 82 supporting the shaft and the control switches. The plate 5| acts between the collar and the frame for resisting rotation of the shaft. When the bevel gear I2 is rotated by the motor through the gears I5, 11, the gear 59 rotates with it and travels around the gear 55. which is held stationary by reason of the plate 8| resisting rotation of the shaft 55. The sleeve member I4 turns with the gear 12 to position the alarm cams 52, 53, and the traveling of the gear 59 around the gear 55 causes the sleeve member II to rotate and position the control cams 45, 4 l.

OJMLDOG The slide-wire of the potentiometer 9 is shown in Fig. 1 as being mounted on a member 98, which is rotated by the motor l9 for positioning the slide-wire relative to the contact 9 which is held stationary. Connected to the power shaft of the motor is a cam 99 which positions a follower 87 fixed to a shaft 99 carrying theindicator or pen arm 20.

In order to indicate the adjustment of the control earns 40, ll, there is provided a cam 90 fixed to the shaft 65 and actuating a follower 9| attached to a shaft 92 carrying an indicating arm 93. The arms 20 and "cooperate with the chart 22 at the face of the plate 90 for indicating the values of the condition measured and the value at which the condition will be when the control cams become effective.

While the control cams are shown mounted on the manually adjustable sleeve H and the alarm cams are mounted on the sleeve 14, it will be understood that the mounting of these cams may be reversed, if desired It is usually desirable that the alarm circuits operate to give warning when the condition reaches certain values regardless of what the values might be when the control circuits operate. The points at which the control circuits operate are more frequently changed, and so the operating cams for such circuits are made readily adjustable. When it is desired to change the operating points for the alarm circuits in the arrangement shown, set screws 95 holding the cams 52, 53 on the sleeve member 14 may be loosened so that the cams may be rotated to new positions on the member.

While there is shown in this application one form which my invention may assume in practice, it'will be understood that it may be modified and embodied in various other forms without departing from its spirit or the scope of the appended claims.

What I claim as new, and desire to secure by Letters Patent of the United States, is:

1. A multiple circuit switch operating mechanism comprising, in combination, three concentrically arranged members supported for rotation relative to each other, means operatively connecting said members so that rotation of either one of two of said members will effect rotation of a third member, manually operable means for rotating one of said two members, means for operatively connecting the other of said two members to an electro-responsive device for rotation thereby, cams connected to said third member for rotation therewith, and a switch operating device arranged for engagement with each cam. 2. A switch operating mechanism adapted for use with an electro-responsive device and comprising, in combination, a shaft, means supporting said shaft for rotation, a pair of sleeve-shaped members concentrically arranged on said shaft and adapted to be rotated relative to each other, differential gearing operatively connecting said shaft and said sleeve-shaped members, manually operable means for rotating said shaft, means connected with one of said sleeve-shaped members for rotation by the electro-responsive device, cams connected to said sleeve-shaped members for respective rotation therewith, and switches arranged for actuation by said cams at predetermined points in the rotation of the latter. 3. A multiple circuit switch operating mechanism adapted for use with an electro-responsive device comprising, in combination, a shaft, means supporting said shaft for rotation, a .pair of sleeve-shaped members concentrically arranged onsaid shaft and adapted to be rotated relative to each other, a member connected to one of said sleeve-shaped members and supporting a bevel gear for rotation on an axis normal to the axis of said sleeve-shaped member, bevel gears fixed to said shaft and to the other of said sleeveshaped members and meshing with said first mentioned bevel gear, manually operable means for rotating said shaft, means connected with said other sleeve-shaped member for rotation by the electro-responsive device, a plurality of cams connected to each of said sleeve-shaped members for rotation therewith, and switch operating devices arranged to be actuated by said cams at predetermined points in their rotation.

4. A multiple circuit switch operating mechanism comprising, in combination, a shaft, means supporting said shaft for rotation, a pair of sleeveshaped members concentrically arranged on said shaft and adapted to be rotated relative to each other, means connected to one of said sleeveshape'd members and supporting a bevel gear for rotation on an axis normal to the axis of said sleeve-shaped member, bevel gears fixed to said shaft and to the other of said sleeve-shaped members and meshing with said first mentioned bevel gear, manually operable means for rotating said shaft, means for connecting said other sleeve-shaped member to a driving motor, a cam fixed to said one of said sleeve-shaped members for rotation therewith, means including a switch adapted to be actuated by said cam at a predetermined point in its rotation for controlling one circuit, a cam fixed to said other sleeve-shaped member for rotation therewith, and means including a switch adapted to be actuated by said last mentioned cam for controlling another citcuit.

5. A multiple circuit switch operating mechanism comprising, in combination, a shaft, means supporting said shaft for rotation, a pair of sleeveshaped members concentrically arranged on said shaft and adapted to be rotated relative to each other, means connected to one of said sleeveshaped members and supporting a bevel gear for rotation on an axis normal to the axis of said sleeve-shaped member, bevel gears fixed to said shaft and to the other of said sleeve-shaped members and meshing with said first mentioned bevel gear, manually operable means for rotating said shaft, friction means operating between the shaft supporting means and said manually operable means for resisting rotation of said shaft, means for connecting said other sleeve-shaped member to a driving motor, a pair of cams adiustably fixed to said One of said sleeve-shaped members for rotation therewith, a pair of switches adapted to be respectively actuated by said pair of cams at predetermined points in their rotation, a pair of cams adJustably fixed to said other sleeveshaped member for rotation therewith, and a pair of switches adapted to be respectively actuated by said last mentioned pair of cams.

- JACK F. SHANNON.

REFERENCES CITED The following references are or record in the file of this patent:

UNITED STATES PATENTS;

Lum July 9, 1999 

